1. Field of the Invention
The present invention relates to an electrosurgical instrument using both high-frequency electric energy and a conductive fluid for coagulating a surface layer of a living tissue by electric discharge through the atomized conductive fluid.
2. Description of the Related Art
Recently, as an electrosurgical instrument using both high-frequency electric energy and a conductive fluid for coagulating a surface layer of a living tissue by electric discharge through the atomized conductive fluid, instruments such as a treatment instrument for an abdominal surgery, a treatment instrument used with a rigid endoscope, a flexible treatment instrument used with a flexible endoscope, and the like are known.
In Japanese Patent No. 3318733, for example, a surgical device is proposed for incision or coagulation of a living tissue by conducting a high-frequency electric current between a nozzle electrode and a portion to be treated through a conductive fluid jet injected from the nozzle electrode toward the portion to be treated.
Specifically, in the surgical device disclosed in Japanese patent No. 3318733, such a construction is provided that, after a discharge column is formed between the nozzle electrode and the portion to be treated, the fluid jet as a focusing flow is injected from the nozzle electrode toward the portion to be treated of a living tissue for incision/coagulation of the living tissue in a non-contact manner from the nozzle electrode using discharge current energy flowing to the portion to be treated through the fluid jet.
Moreover, Japanese Examined Patent Application Publication No. H07-034805 discloses a coagulating device for non-contact hemostatic coagulation of a living tissue from an active electrode by conducting a high-frequency current from the active electrode to the living tissue through the conductive fluid while atomizing the conductive fluid mixed with gas from a distal hole of the active electrode.